Combustion and emission of rapeseed oil blends in diesel engine

Combustion and emission characteristics of rapeseed plant oil (RSO) and its blends with diesel fuel have been investigated in a multi-cylinder direct injection diesel engine. Plant oils have high viscosities compared to diesel and this affects the performance and durability of automotive diesel engines when used for longer time periods. Despite these adverse effects the exhaust emissions analysis show a significant reduction in NOx and relatively higher amount of soot for RSO compared to diesel fuel. An attempt has been made to reduce soot emissions from the combustion of RSO to exploit the advantage of its low NOx emissions. The strategy of varying injection parameters such as injection pressures and injection timings have been used in this work to reduce the soot emissions for blends of 50% and 30% RSO in diesel fuel. Using this strategy it was possible to achieve diesel equivalent levels of soot emission for 30% RSO blend. Under diesel equivalent soot emission levels, it was also possible to achieve a further reduction in NOx emissions by up to 22% for 30% RSO blend, this was achieved at the expense of THC. CO and BSFC. The exhaust soot particle number concentrations for 30% RSO blend reduces with an increase in injection pressure and retarded injection timing. However, when compared to diesel, the exhaust soot particle number concentration for 30% RSO blend was still higher, even after diesel equivalent level of soot emission was achieved. (C) 2012 Elsevier Ltd. All rights reserved.